Weather Application Overview

Introduction

This page provides an overview of a Python weather application that uses several libraries to fetch and display weather data.

Libraries Used

• bs4 (BeautifulSoup): A library for pulling data out of HTML and XML files. It provides easy-to-use methods and Pythonic idioms for searching, navigating, and modifying the parse tree.
• requests: A simple HTTP library for Python. It allows you to send HTTP/1.1 requests easily, without the need to manually add query strings to your URLs, or to form-encode your POST data.
• datetime: A module that supplies classes for manipulating dates and times. With it, you can perform various operations like date arithmetic, formatting, and more. This is built into Python.

You can install these libraries using pip, the Python package installer, with the following commands:

Weather App:

Application Structure

The application is built using PySimpleGUI for the user interface and the aforementioned libraries for backend processing. It works as follows:

1. The user enters a location into the input field and clicks submit.
2. The get_weather_data function fetches weather data from the web.
3. The GUI is updated with the weather information, including an appropriate symbol to represent the current weather conditions.

Key Functions

The get_weather_data function takes a location as input and scrapes weather data using requests to send a query to Google and BeautifulSoup to parse the returned HTML content.

Running the Application

To run the application, execute the script in a Python environment where the required libraries are installed. Ensure that the image files for weather symbols are available in the specified paths.

How the Weather Data Fetching Works

The provided Python code snippet is part of a function that retrieves weather data from the web. Let's break down its functionality and the libraries you need to have installed to run this code.

Code Breakdown

1. User Agent: A user agent string is set to mimic a web browser. This helps in making the server think that the request is coming from a real user using a browser. USER_AGENT = "Mozilla/5.0 ... Safari/537.36"
2. URL Construction: The URL for a Google search query is formulated to include the desired search term, here being 'weather' followed by a location without spaces. url = f'https://www.google.com/search?q=weather+{location.replace(" ","")}'
3. Session Creation: A session is created using the requests library to persist parameters across requests, such as cookies or headers. session = requests.Session()
4. Setting Session Headers: The User Agent is set for the session to the earlier defined string. session.headers['User-Agent'] = USER_AGENT
5. Performing the GET Request:The session sends a GET request to the constructed URL and receives the HTML content of the web page in response. A GET request is one of the most common types of HTTP requests. In the context of the web and networking, a GET request is used to retrieve data from a specified resource on a server. html = session.get(url)

Retrieving and Displaying Weather Data

The Python script uses a graphical user interface (GUI) built with PySimpleGUI to interact with users and display weather information. Here is a step-by-step explanation of what happens when the user submits a location to find out the current weather:

1. Data Retrieval:

   The function get_weather_data() is called with the user's inputted location. It sends a request to a weather service and receives the current weather data, which includes the location's name, the time of the weather data, a brief description of the weather, and the temperature.

   name, time, weather, temp = get_weather_data(values['-INPUT-'])
2. Updating the GUI:

   The GUI elements corresponding to the location, time, and temperature are updated with the new data. This is done using the update() method on each element, identified by their keys, to make them visible and display the retrieved weather data.

   window['-LOCATION-'].update(name, visible = True)
window['-TIME-'].update(f"{time.split(' ')[0]} {datetime.now().strftime('%H:%M:%S')}", visible = True)
window['-TEMP-'].update(f'{temp} \u2103 ({weather})', visible = True)
3. Weather Icon Update:

   Depending on the weather description, an appropriate weather icon is displayed. This is determined by checking if the current weather status matches any condition within a set of predefined weather types (like 'Sunny' or 'Rain'). When a match is found, the corresponding image is updated in the window.

   if weather in ('Sun','Sunny','Clear',...):
  window['-IMAGE-'].update('symbols/sunny.png')

Conclusion

By using these libraries, the code snippet is capable of querying Google for weather information and retrieving the results for further processing in a Python application. Try running this application yourself with a city of your choice!